As is known, many liquid or pourable food products, such as fruit juice, UHT (ultra-high-temperature treated) milk, wine, tomato sauce, etc., are sold in packages made of sterilized packaging material.
A typical example is the parallelepiped-shaped package for liquid or pourable food products known as Tetra Brik Aseptic (registered trademark), which is made by creasing and sealing laminated strip packaging material. The packaging material has a multilayer structure comprising a base layer, e.g. of paper, covered on both sides with layers of heat-seal plastic material, e.g. polyethylene. In the case of aseptic packages for long-storage products, such as UHT milk, the packaging material also comprises a layer of oxygen-barrier material, e.g. an aluminum foil, which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material forming the inner face of the package eventually contacting the food product.
Packages of this sort are normally produced on fully automatic packaging machines, on which a continuous tube is formed from the a web of packaging material; the web of packaging material is sterilized on the packaging machine, e.g. by applying a chemical sterilizing agent, such as a hydrogen peroxide solution, which, once sterilization is completed, is removed from the surfaces of the packaging material, e.g. evaporated by heating; the web so sterilized is then maintained in a closed, sterile environment, and is folded and sealed longitudinally to form a tube, which is fed along a vertical advancing direction.
In order to complete the forming operations, the tube is filled with the sterilized or sterile-processed food product, and is sealed and subsequently cut along equally spaced transversal cross sections within a packaging apparatus of the packaging machine during advancement along the vertical advancing direction.
Pillow packages are so obtained within the packaging apparatus, each pillow package having a longitudinal sealing band and a pair of top and bottom transversal sealing bands.
A packaging apparatus used in packaging machines is known, as described for example in European Patent EP-B-0887265, which comprises a first chain conveyor and a second chain conveyor being spaced apart from each other and defining an advancement space between each other through which the tube passes while being advanced along the advancement direction.
In greater detail, the first chain conveyor has a plurality of first operative units mounted to a first endless chain, adapted to advance along a first endless path and each one comprising a half-shell, a sealing element and an extractable cutting element. The second conveyor comprises a plurality of second operative units mounted to a respective second endless chain, adapted to advance along a second endless path and each one being associated to a respective first operative unit. Each second operative unit comprises a half-shell, a counter-sealing element and a seat. Each first operative unit, in particular the respective half-shell, the sealing element and the extractable cutting element is designed to cooperate with the associated second operative unit, in particular the respective half-shell, the respective counter-sealing element and the respective seat for forming in collaboration the packages.
In more detail, the sealing element is a heating element and the counter-sealing element is made of elastomeric material, which provides mechanical support to grip the tube during the sealing process.
Furthermore, the packaging apparatus comprises a first cam surface arranged in the proximity of the first chain conveyor and adapted to move the first operative units between an operative configuration in which the operative units contact the tube and a rest configuration in which the second operative units are detached from the tube. The packaging apparatus also has a second cam surface positioned in the vicinity of the second chain conveyor and configured to move the second operative units between an operative configuration and a rest configuration. In particular, each one of the first operative units and the respective second operative units cooperate with each other when being in their respective operative configurations.
A drawback of the packaging apparatus disclosed in EP-B-0887265 is the extensive work needed for servicing the packaging apparatus itself. In the case of e.g. a format change the operative units need to be adapted to the new format which requires disassembling of the chains of the first chain conveyor and second chain conveyor for working on the single operative units as otherwise the space available is not sufficient to perform the desired tasks. The disassembling of the chains requires, however, extensive work and leads to rather elevated downtimes of the production.
Similar, in the case of a malfunction of e.g. one operative unit typically at least one of the respective chains of the first chain conveyor and second chain conveyor must be disassembled as a whole. Thus, only after disassembling of the respective chain it is possible to work on resolving the malfunction.
Hence, the servicing of the packaging apparatus disclosed in EP-B-0887265 leads to rather elevated downtimes of the overall production process which again increases the economical losses.